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8954 



Bureau of Mines Information Circular/1983 



Automatic Fire Protection for Mobile 
Underground Mining Equipment 



By Guy A. Johnson 




UNITED STATES DEPARTMENT OF THE INTERIOR 



Information Circular 8954 

n 



Automatic Fire Protection for Mobile 
Underground Mining Equipment 



By Guy A. Johnson 




UNITED STATES DEPARTMENT OF THE INTERIOR 
James G. Watt, Secretary 

BUREAU OF MINES 
Robert C. Norton, Director 







Library of Congress Cataloging in Publication Data: 



Johnson, Guy A 

Automatic fire protection for mobile uiulcTgroimd mining equipment. 

(Bureau of Mines information circular ; 8'>S4) 

Ini. ludcs bibliograpliical references. 

Supt. of Docs, no.: I 28.27!89'S4. 

1. Mining machinery — !■ ires and tire pre\ention. I. litle. II. Se- 
ries: Information circular (United States. Bureau of Mines) . 8954. 



-T^^N^gS.III I-TNSISI 622s[H22\8| 83 600271 



CONTENTS 

Page 

Abstract 1 

Introduction 1 

Design concept 2 

In-mine fire test 6 

Alternative system designs. 6 

Availability 12 

Conclusions 12 

ILLUSTRATIONS 

1 . Typical components of an automatic system 2 

2 . System schematic 3 

3. First-generation design concept 4 

4 . Laboratory testing a thermal fire sensor 5 

5 . Fire testing on load-haul-dump engine mockup 5 

6. Installing first-generation system on underground load-haul-dump at Lake- 

s hor e Mine 6 

7. System control box on underground vehicle 6 

8. Fire pan above the engine area on test vehicle 7 

9. Filling fire pans prior to on-vehicle fire test 7 

10. Lighting the underground test fire with a propane torch 8 

11. Flame from the test fire in the engine area 8 

12. Automatically extinguishing the test fire 9 

13. After the test fire is extinguished 9 

14. Alternative system for small load-haul-dump 10 

15. Alternative system for large load-haul-dump 10 

16. Alternative system for underground haulage truck 10 

17. Alternative system for underground lubrication truck 10 

TABLE 

1. In-mine, proof -of -concept testing of automatic fire protection systems for 

underground vehicles 11 



AUTOMATIC FIRE PROTECTION FOR MOBILE UNDERGROUND MINING EQUIPMENT 

By Guy A. Johnson 



ABSTRACT 

To improve productivity and cut costs, modern underground mining oper- 
ations have become more mechanized. This mechanization has increased 
the usage of fuels, hydraulics, and electrical equipment associated with 
diesel-powered vehicles, thereby also increasing the hazards of under- 
ground mine fires. The Bureau of Mines evaluated the fire hazard prob- 
lem and assembled prototype components for a system that would auto- 
matically sense and extinguish fires on mobile underground equipment. 
The prototype system and alternative designs were in-mine-tested and 
proved effective. This report summarizes this technology, which can 
cost effectively help solve the problem of fire hazards on underground 
vehicles. 

INTRODUCTION 

As part of its fire and explosion program, to help ensure safer work- 
ing conditions for miners, the Bureau of Mines has spent several years 
studying improved fire protection for mobile equipment used in surface 
mining. With the basic R&D completed, the Bureau is now working with 
the Mine Safety and Health Administration (MSliA) , the National Fire Pro- 
tection Association (NFPA) , and fire equipment manufacturers to refine 
this technology. Building upon this effort, the Bureau has also com- 
pleted a project to improve fire protection for mobile equipment used in 
underground mining. This work was undertaken because the danger of 
underground fires has recently increased as a result of increased usage 
of fuels, hydraulics, and electrical equipment associated with diesel- 
powered vehicles. Specific initiative came in 1976 when the mining in- 
dustry had two fatalities because of a fire on a load-haul-dump (L-H-D) 
at Hecla's Lakeshore copper mine near Casa Grande, AZ. The Bureau had 
already investigated the basic technology for rugged fire protection for 
large surface mining machines like haulage trucks, front-end loaders, 
draglines, shovels, etc.; this technology, though, needed to be modified 
so it could be applied to the diesel-powered underground mobile raining 
equipment. 

a 

'Supervisory mining engineer. Twin Cities Research Center, Bureau of Mines, Minne- 
apolis, MN. 



DESIGN CONCEPT 



Manually activated fire protection sys- 
tems that use fixed piping and dry chemi- 
cals have been used on underground vehi- 
cles for a number of years and have had 
some success. The manual systems are 
reliable but require someone to activate 
them. Some vehicle operators may panic 
during a fire emergency and fail to actu- 
ate the system. Therefore, for greater 
reliability, automation is needed. Using 
the manually activated systems as a 
starting point, the Bureau added sensors 
and automatic controls so that a fire 
would be sensed by on-board thermal 
sensors and suppressed automatically 
(i.e., when it was still small and 
controllable) . 

The automatic fire protection systems 
utilize a multipurpose, dry chemical 
fire-suppressing agent. This fire extin- 
guishant is effective on fires involving 
combustibles on a vehicle and is commonly 
used underground; thus, mine personnel 



are comfortable with it. Typical compon- 
ents of an automatic system are shown on 
figure 1. The system shown would auto- 
matically shut down the engine and set 
the brakes in the event of a fire. 

Since no one system could solve every 
type of fire hazard, the design concept 
(figs. 2-3) was developed to be very ver- 
satile, so that mines would have the 
flexibility to fabricate a system commen- 
surate with their needs. During the com- 
ponent selection phase of this R&D, tests 
were run in the laboratory to investigate 
the timing required by various thermal 
sensors to sense a typical vehicle fire 
(fig. 4). A mockup of the engine com- 
partment of a typical L-H-D was then 
built and tests were run to determine the 
amount of dry chemical agent needed to 
extinguish a typical fire (fig, 5). The 
prototype hardware performed well; thus, 
the next step was actual on-vehicle test- 
ing underground. 



-Dashboard manual actuator 
Electrical actuator 



Control panel 




Remote manual actuator 

Spot-type thermal sensor 

Linear thermal sensor 
Nozzle 



Agent tanks- 




FIGURE 1. - Typical components of an automatic system. 




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FIGURE 4. - Laboratory testing a thermal fire sensor. 




FIGURE 5. " Fire testing on load-haul-dump engine mockup. 



IN-MINE FIRE TEST 



In 1911 y the Bureau installed the 
first-generation prototype system on an 
L-H-D (fig. 6) at the Lakeshore Mine, 
then operated by Hecla Mining Co. near 



Casa Grande, AZ. 
control unit (SCU) 
warn the driver of 
matically set off 
driver abandoned the 



This system had a 
(fig. 7) that would 
a fire (and auto- 
the system if the 
vehicle) , thermal 



sensors in the vehicle's engine, articu- 
lation, and transmission areas, and pip- 
ing to distribute the dry chemical fire 
suppressant. 



After 1 year of successful on-vehicle 
testing (i.e., no accidental actuations), 
pans were installed on the vehicle and 
filled with heated hydraulic oil prior to 
an actual in-mine, on-vehicle fire test 
(figs. 8-9). Figure 10 shows the light- 
ing of the fire in the vehicle's engine 
area. The system sensed the test fire 
(fig. 11), sounded the alarm, and auto- 
matically extinguished the fire (figs. 
12-13). This in-mine fire testing was 
conducted in close cooperation with both 
mine and MSHA personnel. 



ALTERNATIVE SYSTEM DESIGNS 



In 1979, 1980, and 1981, numerous 
design alternatives were studied and in- 
mine-tested to demonstrate to the in- 
dustry the flexibility and reliability of 



this technology. These systems were 
evaluated on different sizes of L-H-D' s, 
an underground truck, and a lubrication 
truck (figs. 14-17.) 




FIGURE6. - Instal ling first-generation system on 
underground load-haul-dump at Lakeshore Mine. 
Typical components of the system are shown in 
figure 1 . 




FIGURE 7. - System control box on underground 
vehicle. Location of control panel is shown in 
figure 1. 




FIGURE 8. - Fire pan above the engine area on test vehicle. 




FIGURE 9. - Filling fire pans prior to on-vehicle fire test. 




FIGURE 10. - Lighting the underground test fire with a propane torch (outlined), 




FIGURE 11. - Flame from the test fire (outlined) in the engine area. (Approximately 1 min after 
lighting.) 




^HP"-- 'W^ 




FIGURE 12. - Automatically extinguishing the test fire. (Approximately 2 min after lighting,) 




FIGURE 13. - After the test fire is extinguished. (Approximately 4 min after lighting.) 



10 



Check valves (2) 



Detection cable 




Control console 

Dashboard actuator 

Check valves (2) 



30-lb dry chemical tank 
Electric actuation device 



' Nozzles 
Air cylinder (fuel shutoff ) 




FIGURE 14. - Alternative system for small 
load=haul-ciump. 



30-lb dry 
chemical tank 




- Dashboard actuator 
Control consote 



Detection cable 
(ttiermal) 

Nozzles (2) 



Electric actuatkxi device 
Air cy(nder (fuel shutoff) 




FIGURE 15. - Alternative system for large 
load-haul-dump. 



- Air cylinder (fuel shutoff) 

- Control valve (set brakes) 

• Nozzles 

■ Detection cable (ttiennal) 



Control console 

1 2 vdc 
■ Dashboard actuator 
Check valves 
30-lb dry chemical tank 

Electric actuation tank 





FIGURE 16. - Alternative system for underground 
haulage truck. 



Horn-lamp 
SCU 



LT-LP-101-20 
ctwmical tank 



Squib actuator 
Detector kx)p 

-Nozzles 




Hand-portable fire extinguist)er 

FIGURE 17. - Alternative system for underground 
lubrication truck. 



11 



Table 1 summarizes this follow-on work, 
which tested system designs on seven 
types of vehicles in four underground 
mines. The individual tests lasted from 



10 to 34 months and total 158 months of 
debugging, redesign, and final proof -of - 
concept testing of prototype hardware. 



TABLE 1. - In-mine, proof -of -concept testing of automatic fire protection systems 
for underground vehicles 



Mine 



Vehicle-'- 



Dates 



Comments 



Hecla Mining Co., Lake- 
shore (copper) Mine, 
Casa Grande, AZ. 



Do, 



Bunker Hill Mining Co., 
Bunker Hill (lead-zinc) 
Mine, Wallace, ID. 



Do. 



Do. 



Morton Salt Co. , Grand 
Saline (salt) Mine, 
Grand Saline, TX. 



Union Carbide Corp. , 
Pine Creek (tungsten) 
Mine, Bishop, CA, 



Wagner ST-2B 
L-H-D. 



iQO» •••••••• 



Eimco L-H-D. 



In-house modi- 
fied TO- 2 
hauler. 

Plymouth DMD- 
24 diesel 
locomotive. 



Caterpillar 

450-f ront-end 
loader. 



Getman lube 
truck. 



May 1976- 
July 1978 



May 1977- 
July 1978 



Mar. 1978- 
Nov. 1980 



Aug. 1979- 
Nov. 1980 



Mar. 1978- 
Nov. 1980 



Apr. 1978- 
Nov. 1980 



Apr. 1980- 
Feb. 1981 



The 26 months of testing showed 
that the basic system design 
was good, but an improved ac- 
tuation device was needed. 

Tests on a 2d vehicle with pro- 
totype hardware with an im- 
proved actuation device proved 
successful. Testing termin- 
ated with closure of the mine. 

The hardware was retrofitted in 
August 1979 with the Squib 
electric actuation device, 
which proved to be the best 
actuation device tested. 

This system also had the Squib 
electronic actuation device 
retrofitted in August 1979. 

A preproduction Squib electron- 
ic actuation device system was 
successfully tested for 14 
months. 

The Squib electric actuation 
device was retrofitted to this 
2d-generation prototype in 
September 1979. 

Another preproduction model of 
the automatic fire protection 
system for underground vehi- 
cles was successfully tested. 



^Reference to specific equipment or manufacturers does not imply endorsement by the 
Bureau of Mines. 



NOTE. — 6 systems were tested on 7 vehicles in 4 underground mines. The tests 
ranged from 10 to 34 months in length. A total of 158 months of in-mine work helped 
to develop and debug prototype hardware. Some problems occurred with false actua- 
tions (most of which were traced to "horseplay" by miners trying to see how much heat 
the system could sense before going off), but the final system proved rugged enough 
for long-term, in-mine use at a reasonable cost. 



12 



AVAILABILITY 



As a result of this work, automatic 
fire protection systems are currently 
available from several manufacturers. 
These systems cost between $2,000 and 
$4,000 installed. 2 The NFPA of Quincy, 
MA, which has written the Life Safety 
Code and the National Electric Code, is 
currently planning to write consensus in- 
dustry standards to address the problems 



of fire protection in underground mines, 
utilizing the Bureau's in-mine-proven 
research results. 



More detailed information 
from two technical reports 



is available 
on the Bu- 



reau's research and testing of this 
technology .3 



CONCLUSIONS 



In cooperation with many mining compan- 
ies and fire protection equipment manu- 
facturers, the Bureau has investigated 
and in-mine-tested automatic fire protec- 
tion systems that have proven effective 
for underground vehicles. The choice of 
what system to use depends on vehicle use 
patterns and duty cycles, maintenance 
requirements, vehicle dimensions, and the 
locations of the vehicle's fire hazard 
(usually the engine compartment) and the 
operator's station. 

As a result of this Bureau work, vari- 
ous levels of sophistication in automatic 
systems are now commercially available. 
These range from basic detection and dry 
chemical suppression systems to sys- 
tems with redundant sensing, visual and 

•^The Bureau purposely worked with more 
than one component manufacturer, to keep 
commercial competition high and pricing 
low. 



audible operator alarms , delayed dis- 
charge, machine power shutdown, circuit 
fault warning, and self-contained backup 
power supply, all with manual discharge 
capability. An analysis of the specific 
fire protection requirements for a given 
application will aid in selection from 
among this list of system options. 

-^McDonald, L. A. , and G. R. Reid. Au- 
tomatic Fire Protection System for Mo- 
bile Underground Metal Mining Equip- 
ment (contract HO252038, Ansul Co.). 
Vol. II. Long Term Validation Testing. 
BuMines OFR 159-82, 1981, 242 pp.; 
NTIS PB 83-1 14876. 

Reid, G. R. , D. L. Stockwell, and 
R. J. Plog. Development of an Automatic 
Fire Protection System for Mobile Under- 
ground Metal Mining Equipment, Phase 
II Report (contract HO252038, Ansul 
Co.). BuMines OFR 81-76, 1975, 151 pp.; 
NTIS PB 254 851. 



INT. BU.OF MINES,PGH.,P A. 27160 



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